A dual view type liquid crystal display disclosed in each of Patent Citations 1 and 2 described below is known in the field of image display technology. Meanwhile, various types of operation panel having a touch screen via which an operation command is entered have been conventionally known. Developed in recent years is an operation panel whose touch screen is constituted by the dual view type liquid crystal display, as disclosed in each of Patent Citations 1 and 2.
[Patent Citation 1]
Japanese Unexamined Patent Publication Tokukai 2005-284592 (published on Oct. 13, 2005)
[Patent Citation 2]
Japanese Unexamined Patent Publication Tokukai 2005-078076 (published on Mar. 24, 2005)
FIG. 1(a) is a front view schematically illustrating a display screen of such a dual view type liquid crystal display. FIG. 1(b) is a perspective view of the display screen. FIG. 1(c) is a top view of the display screen. The wording “dual view type” refers to such a view type of simultaneously displaying (i) a first image in a first direction on the display screen 100 of the liquid crystal display and (ii) a second image, different from the first image, thereon in a second direction different from the first direction as shown in FIG. 1.
As shown in FIG. 1(c), in such a dual view type liquid crystal display, a viewing angle a of the first image displayed in the first direction is different from a viewing angle b of the second image displayed in the second direction. Therefore, it is impossible to view and recognize the second image in a viewing position 150 where a user can view and recognize the first image. On the other hand, it is impossible to view and recognize the first image in a viewing position 200 where the user can view and recognize the second image.
When the user's eyes (viewer's eyes who sees the liquid crystal display) are positioned in an intermediate point 300 between the viewing positions 150 and 200, an indistinct image in which the first and second images are mixed with each other is presented to the user, with the result that the user can recognizes neither the first image nor the second image from this indistinct image.
That is, the dual view type liquid crystal display suffers from such a problem that the user cannot simultaneously view the first and second image even when he/she needs to view them simultaneously.